Known in the prior art are devices for surface fusion treatment of products made of artificial stone materials, comprising an oxyacetylene burner or a plasma generator and a mechanism for relative displacement of the burner or generator and the product (cf. USSR Author's Certificate No. 339421 and the Hungary Pat. No. 172 563). As the surface layer is fused by such devices the burner flame or the plasma jet is directed to the surface being treated. In so doing, the surface layer fusion takes place within the contact spot of the burner flame or the plasma jet and the surface being treated, and therefore, the productivity of said devices provided with a single burner or generator is relatively low. The use of a plurality of oxyacetylene burners or plasma generators in a single device complicates the design and reduces the reliability of such a device.
Also known in the art are devices for surface fusion treatment of products made of artificial stone materials, and producing an arc discharge of a plasma generator along the surface being treated, thus enhancing the treatment productivity as compared to that of the devices described hereinabove. A device is known which comprises separately mounted anode and cathode assemblies of a plasma generator, directs the arc discharge transversely to the longitudinal axis of an anode shaped as an elongated body, and displaces the arc discharge along this axis (cf. U.S. Pat. No. 3,584,184). In the device in question, the anode is made as a rectangular box while the cathode is made as a pin installed so as to be directed towards the anode at an acute angle to the plane of arrangement of the surface being treated on the working zone side. The anode is fixed, while the cathode is movable along the anode and is coupled with a mechanism providing reciprocating motion thereof in that direction. When the surface of the product is treated, the product is moved from the cathode towards the anode as sequential sections of the surface have been treated with the cathode being moved in one direction.
In the described prior art device having the discussed arrangement of the cathode, the arc discharge occurs along a curved line through a surface layer of the product being treated. This is necessary to provide, using the electric conductivity of the fused material, a deep fusion of the product being treated. However, when a relatively thin surface layer is fused by a convective and radiative heat exchange between the surface being treated and the arc discharge, the arc discharge will work effectively only with a portion of the length thereof, which reduces the width of the surface section being treated and leads to considerable plasma heat energy losses. At the same time the effective fusion of surface layer cannot be achieved with the use of the described prior art device, since the arrangement of the cathode in parallel with the surface does not permit the use of the entire length of the arc discharge as required to treat large surfaces having dimensions, in the direction of both axes at right angles to each other, that are longer than the spacing between the cathode and the anode. This is caused by the fact that in the described device the arc discharge passes through the cathode axis, and, therefore, with consideration for the transverse dimensions of the anode and cathode assemblies, the arc discharge is far removed from the surface being treated.